The former Expedia CEO's appointment comes after the embattled Uber cofounder Travis Kalanick was ousted as CEO of the world's most valuable private company in June. Uber has suffered an exodus of its top ranks amid mounting public and legal scandals.

"I am excited to welcome Dara Khosrowshahi as Uber's next CEO," Kalanick said in a statement on Tuesday. "With a deep passion for team building, Dara grew Expedia into one of the world's most successful travel and technology platforms. Casting a vote for the next chief executive of Uber was a big moment for me and I couldn't be happier to pass the torch to such an inspiring leader."

In a memo sent to Uber employees, the company's board called Khosrowshahi "the best person to lead Uber into the future" and said his appointment was also aimed at "improving our culture and making Uber the best place to work."

Expedia couldn't immediately be reached for comment.

Khosrowshahi was the dark horse in Uber's chaotic and highly publicized CEO search. HP Enterprise CEO Meg Whitman and former GE CEO Jeff Immelt were the other two candidates considered by the board for the role over the past weekend.

Khosrowshahi, 48, has been CEO of Expedia for 12 years, during which he turned it into the biggest online travel agency in the US. An Iranian immigrant who moved to New York as a kid, he started his career at the investment bank Allen & Co. before serving as CFO at the media company IAC.

Now that his new CEO job is official, Khosrowshahi will greet Uber employees at an all-hands meeting at the company's San Francisco headquarters on Wednesday.

We are delighted to announce that Uber's Board has voted unanimously to appoint Dara Khosrowshahi to be our new CEO.

Dara came to America at nine years old when his family escaped Iran on the eve of the Iranian Revolution. He grew up in Tarrytown, N.Y., trained as an engineer at Brown, and spent many years at IAC serving as Chief Financial Officer and in various operational and strategic roles.

In 2005, he became CEO of Expedia, which he built into one of the world's leading travel and technology companies, now operating in more than 60 countries. He has four children and not surprisingly loves to travel, one of his favorite trips being to the Angkor Wat temples in Cambodia where his wife Sydney said yes to marrying him.

We're really fortunate to gain a leader with Dara's experience, talent and vision. The Board and the Executive Leadership Team are confident that Dara is the best person to lead Uber into the future building world-class products, transforming cities, and adding value to the lives of drivers and riders around the world while continuously improving our culture and making Uber the best place to work.

Dara will be joining us tomorrow, August 30, for an All Hands. Add your questions for Dara here, and stay tuned for a calendar invite with more details. He'll also be meeting with employees around the world in smaller groups over the next few weeks, and spending time with drivers.

Please join us in welcoming Dara on what promises to be an exciting ride!